This invention relates to catheters and more particularly to catheter apparatus utilizing optical imaging arrangements for the sensing and analysis of tissue or particulate samples in a medium.
Mammalian vessels are subject to damage by atherosclerotic plaque, vascular lesions, and aneurysms. Such plaque may be simple plaque or vulnerable plaque. Vulnerable plaque consists of lipid-rich core material and inflammatory cells. These vulnerable plaques are prone to rupture and erosion. Sixty to seventy percent of fatal myocardial infarctions are triggered by plaque rupture. In about twenty five to thirty percent of fatal infarctions, plaque erosion or ulceration is the triggering mechanism. Erosion occurs when the endothelium beneath the thrombus is replaced by inflammatory cells. Such inflammatory cells are commonly associated with plaque rupture and ulceration. Plaque rupture and ulceration may respond to and aggravate intimal injury, promoting thrombosis and vasoconstriction.
Vulnerable plaques, which pose a significant risk of precipitating infarction, occur in coronary arteries which may appear apparently normal or only mildly stenotic on angiograms. Thus, detection of these vulnerable plaques prior to any rupture or erosion would present a significant advance in the treatment of a mammalian patient.
The present invention relates to a catheter based system for the optical analysis of mammalian vessels, tissue samples and methods of utilization of that catheter based system. Such a catheter based system is utilized to independently deliver and collect optical radiation through an arrangement of optical fibers in such a manner that the radiation delivered and collected by those optical fibers is known and may be controlled.
The catheter based optical system of the present invention comprises a light source such as a laser or the like, for example a titanium sapphire laser in optical communication with an optical coupler. The catheter based optical system includes and elongated catheter having a distal end and a proximal end. The catheter comprises an outermost sheath of thin resilient material having proper columnar strength, the distal end of which is formed of polyethylene or other biocompatible material, and is optically transparent. An elongated optical delivery fiber arrangement is disposed from the proximal end of the catheter through and into the distal end thereof. An optical collection fiber arrangement is also disposed within the catheter sheath alongside the optical delivery fiber arrangement. The optical delivery fiber arrangement has a distal end which is in optical communication with an optical re-director within the distal end of the catheter sheath. The optical delivery fiber arrangement has a proximal end which is in optical communication with the optical coupler at the proximal end of the catheter shaft. The optical collection fiber arrangement has a distal end which is in optical communication with the optical re-director within the distal end of the catheter sheath. The optical collection fiber arrangement has a proximal end which is in optical communication with the optical coupler at the proximal end of the catheter sheath. The optical re-director at the distal end of the catheter sheath is arranged to re-direct light traveling through the optical delivery fiber arrangement and generally radially outwardly through the sidewall of the catheter sheath, and onto a vessel wall of a mammalian subject undergoing the test procedure.
A reflected light path receiving member may be arranged in the optical re-director a spaced distance apart from the optical delivery path within the optical re-director. The receiving member collects the reflected light from any tissue within the mammalian vessel and communicates it proximally through the optical collection fiber arrangement for transmission into the optical coupler.
A detector is in communication with the optical coupler, to receive the optical radiation from the optical collector fiber arrangement and convert that signal into an electronic display. The electronic display is presented as an analysis of the tissue structure within the vessel being examined within the mammalian host.
In a further embodiment of the present invention, a rotatable optical coupler is arranged in optical communication between the optical coupler and the proximal ends of the optical delivery fiber arrangement and the optical collection fiber arrangement. The rotatable optical coupler, in this embodiment, may be configured as an optical slip ring generally somewhat similar to those arrangements as may be seen in U.S. Pat. No. 4,109,998 to Iverson or in U.S. Pat. No. 4,725,116, to Spencer et al. or to U.S. Pat. No. 4,872,737, to Fukahori et al., each of which patents are incorporated herein by reference in their entirety. In this embodiment, both the optical delivery fiber arrangement and the optical collection fiber arrangement are each rotated simultaneously about an elongated axis of rotation which is co-axial with the longitudinal axis of the catheter sheath. In this embodiment, the optical re-director also rotates within the distal end of the catheter sheath.
The optical re-director may be comprised of right angled extensions or of diagonally arranged mirrors disposed at the distal end of each respective optical collection fiber arrangement and optical delivery fiber arrangement. The distal end of each fiber arrangement respectively emits and collects optical radiation in an independent and separate manner with respect to the inner wall of the vessel of the mammalian patient into which the catheter apparatus is being worked. The distal ends of each fiber arrangement are spaced apart from one another along the longitudinal axis of rotation of the fiber assembly. The use of independent fibers for delivering and for collecting optical radiation permits control of the separation between where the point of the optical radiation impinges upon the tissue sample of the vessel and the point where the optical radiation is collected from the tissue sample of the vessel. Such an optical fiber arrangement may be in the order of two to three microns in diameter to as much as two to three millimeters in diameter. In a further contemplative embodiment, the optical delivery fiber arrangement may be comprised of a plurality of individual elongated optical fibers which collectively comprise the optical delivery fiber arrangement. In a similar manner, the optical collection fiber arrangement may be comprised of a plurality of individual optical collection fibers.
In a further preferred embodiment of the present invention, the optical collection fiber arrangement may be of a different, i.e. a greater diameter than the optical delivery fiber arrangement to permit weaker signals to be transmitted therethrough without loss of a signal strength.
In yet a further object of the present invention, it is contemplated that the optical delivery fiber arrangement and the optical collection fiber arrangement be in a coil with respect to one another. That is, the delivery fiber arrangement may be arranged as an inner coil twisted in a one hand direction with the collection fiber arrangement disposed as an outer coil of an opposite hand direction or as a twisted pair, to provide columnar strength to the catheter sheath during its insertion within the mammalian vessel, and to provide stability while permitting the minimization of the diameter of the catheter sheath that would otherwise require wall reinforcement and reinforced guideability.
In a further embodiment of the present invention, the optical delivery fiber arrangement and the optical collection fiber arrangement may be coaxial, and separated by a reflecting or containing cladding arranged therebetween. A containing cladding may also be arranged on the outer peripheral surface of the combined delivery fiber and collection fiber arrangement arranged rotatably within the catheter sheath. Such an embodiment may include the delivery fiber arrangement comprising the inner core of the collective optical fiber arrangement assembly. Such a coaxial fiber arrangement would be in optical communication with an optical slip ring coupler arrangement wherein an inner or outer fiber arrangement acts as the delivery medium and the outer or inner fiber arrangement acts as the collection fiber arrangement for transmission to a detector for conversion to a proper electrical signal for analysis of the mammalian vessel wall.
Thus the invention comprises a catheter based optical system for generating data as to the condition of tissue of a mammalian vessel, comprising an elongated catheter shaft having a tissue engaging distal end and a coupled proximal end. An elongated optical delivery fiber is arranged through a lumen of the catheter. The optical delivery fiber arrangement has a distal end and a proximal end. The distal end of the delivery fiber arrangement has a re-director light emitter thereon for directing light against the mammalian tissues. An elongated optical collection fiber arrangement is also disposed through a lumen of the catheter, the optical collection fiber arrangement having a distal end and a proximal end. The distal end of the collection fiber arrangement has a re-director light receiver thereon for receiving light reflected from the mammalian tissue by the light emitter. The light emitter and the light receiver are longitudinally spaced apart from one another in the distal end of the catheter. The catheter apparatus includes a light source in communication with the delivery fiber and a signal detector in communication with the receiving fiber for receiving and presenting the data collected. The elongated delivery fiber arrangement and the elongated collection fiber arrangement may rotate about a common longitudinal axis within the elongated catheter shaft. The delivery fiber arrangement may be of a different diameter than the diameter of the collection fiber. The catheter apparatus may include a rotary optical coupler arranged between the light source and the delivery fiber arrangement. The rotary optical coupler may also be arranged between the collection fiber arrangement and the signal detector. The delivery fiber arrangement and the collecting fiber arrangement may form a coiled pair. The delivery fiber arrangement may be comprised of a plurality of individual delivery fibers. The collection fiber arrangement may be comprised of a plurality of individual collection fibers. The light emitter at the at distal end of the delivery fiber arrangement may include a rotary optical coupler arranged to direct light from the delivery fiber arrangement to the tissue and to direct light reflected from the tissue into the collection fiber arrangement. The rotary optical coupler may comprise a beam splitter. The delivery fiber arrangement and the receiving fiber arrangement may be co-axially arranged with respect to one another. The delivery fiber arrangement and the receiving fiber arrangement may be separated by a containing cladding arranged therebetween. The delivery fiber arrangement and the receiving fiber arrangement may be longitudinally enclosed by a containing cladding.
The invention may also include a method of generating data as to the condition of tissue of a mammalian vessel by a catheter based optical system comprising the steps of: arranging an elongated catheter shaft having a tissue engaging distal end and a coupled proximal end in a mammalian vessel to be examined; placing an elongated optical delivery fiber arrangement through a lumen of the catheter, the optical delivery fiber arrangement having a distal end and a proximal end; the distal-most end of the delivery fiber arrangement having a re-director light emitter thereon for directing light against the mammalian tissues; arranging an elongated optical collection fiber arrangement through a lumen of the catheter, the optical collection fiber arrangement having a distal end and a proximal end, the distal end of the collection fiber arrangement having a re-director light receiver thereon for receiving light reflected from the mammalian tissue by the light emitter; the light emitter and the light receiver may be longitudinally adjustably spaced apart from one another in the distal end of the catheter; and connecting a light source into optical communication with the delivery fiber arrangement and a signal detector in communication with the receiving fiber arrangement for receiving and presenting data collected. The method may include the steps of: rotating the collection fiber arrangement and the delivery fiber arrangement about a common axis within the catheter; connecting the collection fiber arrangement and the delivery fiber arrangement to an optical slip ring for communication of optical signals sent from the light source and returned to the detector for presentation and analysis thereof; and twisting the delivery fiber arrangement and the collection fiber arrangement into a coil about one another.
The invention also includes a method of generating data as to the condition of tissue of a mammalian vessel by a catheter based optical system comprising the steps of: inserting an elongated optical delivery fiber and a separate elongated collection fiber into the catheter, each of the fibers having a proximal and a distal end, each distal end of each of the fibers having a light re-director thereon; attaching a rotary optical pickup to the proximal ends of each of the fibers in the catheter so as to be in optical communication therewith; attaching a light source to the rotary optical pickup so that the light source is in light communication with the light redirectors at the distal end of the fibers; inserting the catheter into a mammalian vessel; energyzing the light source to provide light through the delivery fiber to the re-director and onto the tissue; reflecting the light from the tissue into the re-director on the distal end of the collection fiber; receiving the reflected light through the rotary pickup; and directing the received light into a signal detector for analysis of mammalian tissue thereby. The method may include the step of rotating the delivery fiber and the collection fiber about a common axis so as to permit a circumferential scan of mammalian tissue in the vessel. The method may include the step of spacing the re-directors apart by a longitudinal distance within the catheter to effect reflection characteristics of the light collected. The method may include the step of adjusting the longitudinal distance apart of the redirectors by an adjustment arrangement at the proximal end of the catheter. The method may also include he step of: placing one of the optical fibers within the other of the fibers so as to effect a co-axial arrangement therebetween. The method may include the step of: placing a containment layer between the optical fibers to prevent optical light exchange therebetween.
It is an object of the present invention to provide an improvement in the recognition and treatment of vulnerable plaque in mammalian systems over that which has been shown in the prior art.
It is a further object of the present invention to provide a catheter based system for the optical analysis of mammalian vessels.
It is yet a further object of the present invention to provide a fiberoptic arrangement within a catheter system which may be adaptable for individual vessel analysis.
It is still yet a further object of the present invention to provide a catheter based optical analysis of mammalian vessels when fiberoptic components are utilized to facilitate the positioning of the catheter apparatus.